Version 4.7 When switching the window manager the wrapper plugins (external plugins) are not displayed and have a default grey background from the gtk theme instead. It can be reproduced by running xfwm4 --replace&disown. To get the plugin "visible" again it is possible to restart the panel from the right click menu.
I can't reproduce this. Please try with "xfconf-query -c xfce4-panel -p /force-all-external -t bool -n -s true", maybe only a single plugin is not working after a window manager switch.
Created attachment 2869 Screenshot of panel after replacing the window manager The plugins are displayed well, but the background color remains solid/opaque. On another note, the size for the notes icon isn't reset properly but I'll first have a look inside the plugin itself.
I think this was related to compositing changes. Plugin are now restarted when the window is unrealized/realized again. Could you give this a shot?
Works just fine.